GB2116890A - Restrained mandrel mill inlet table - Google Patents

Description

1 GB 2 116 890 A 1

SPECIFICATION

Restrained mandrel mill inlet table This present invention relates to a restrained mandrel mill for seamless tubes and more particularly to a roll 5 lifting apparatus for a restrained mandrel mill inlet table.

The restrained mandrel mill is such that a mandrel bar is inserted through a hollow shell (hereinafter referred to as a shell) obtained by piercing the billet by a piercing mill or a shell elongated by any other elongating mill and the shell is passed into a continuous rolling mill including usually six to nine consecutive stands of two-high orthree-high rolls thereby continuously rolling the shell between the mandrel bar and the 10 rolling rolls to the desired tube size. During the rolling of the shell, the axial (lengthwise) movement of the mandrel bar is controlled (restrained).

There are many different methods of using the mandrel bar such that after completion of the rolling, while the shell is passed to the next operation, the mandrel bar is pulled back to the rolling preparation position where it is cooled, coated with a lubricating oil and then inserted again into the next shell, the mandrel bar is 15 pulled back to the initial position before the start of the rolling where it is uncoupled with the restrained bar and then it is side shifted from the pass line, or at the rolling ending position the mandrel bar is uncoupled with the restrained bar, moved forward in this condition, side shifted from the pass line after passing through the mill, cooled, coated with a lubricant and then used repeatedly. 20 With this type of mandrel mill, an inlet table of as long as several tens meters is arranged at the entry side 20 of the mill and rolls are arranged on the inlet table so as to support the shell and the mandrel bar which are moved at a high speed along the pass line. Figures 1 and 2 are schematic side views showing a prior art inlet table by way of example. In the Figures, numeral 1 designates a mandrel bar, and 2 a shell into which the mandrel bar is inserted. Numeral 31 25 designates a restrained bar coupled to the mandrel bar 1 to pass the shell 2 and the mandrel bar 1 between 25 rolling rolls 41,41 a and 42,42a of a rolling mill 4 and control (restrain) the movement of the mandrel bar 1 during the rolling of the shell 2, having at the top thereof a coupler adapted for engagement with the bottom of the mandrel bar 1 and driven in the forward and backward, respectively, at a high speed along the pass line by means of chains or motor driven gears which are arranged on both sides of the bar and not shown.

Designated at T is an inlet table having arranged thereon a plurality (7 in the Figures) of roll units 5 each 30 including a roll 53 rotatabiy mounted on two arms 52 rotatably mounted on a shaft 51, and also pinch rolls 54 are located atthe inlet end of the rolling mill 4. (Hereinafter the roll units may possibly be designated by reference numerals (1) to (2)). Numeral 55 designates a hydraulic cylinder whose operating rod 56 is connected to the arms 52 (while, in the Figures, only the single hydraulic cylinder 55 is shown by way of a typical example, the similar hydraulic cylinder is connected to the arms 52 of each roll unit). The most of the 35 rolls 53 are driven in the forward and reverse directions to move the mandrel bar 1 and the shell 2 and some of the rolls 53 serve as idler rolls.

Then, just before the time that the mandrel bar 1 and the shell 2 are moved forward in the direction of an arrow a by the restrained bar 31 and the shell 2 is moved into the rolling mill 4, the rolls 53 of the roll units (D to @ are supporting the mandrel bar 1 and the shell 2 as shown in Figure 1.

In this case, the thickness t3 of the restrained bar 31 below the pass line P - P (the half of the whole thickness) is greater than the thicknesses (radii) t, and t2 of the mandrel bar 1 and the shell 2 below the pass line P - P. Thus, if, in this condition, the restrained bar 31 is advanced in the arrow a direction, there is the danger of the top of the restrained bar 31 striking against the rolls 53 of the roll units 5 thus damaging the restrained bar 31 and the shell 2, bending the mandrel bar 1 or causing any other serious fault.

As a result, the top position of the restrained bar 31 is detected and a signal is sent to each of the hydraulic cylinders 55, thus operating the hydraulic cylinder 55 of each roll unit just before the restrained bar 31 reaching the roll thereof and rotating the arms 52 about the shaft 51 in a counterclockwise direction and thereby causing the roll 55 to clear and avoid its collision with the restrained bar 31. Similarly, when the mandrel bar 1 is moved backward in the direction of an arrow b, the position of the backwardly moving restrained bar 31 is detected and a signal is sent to the hydraulic cylinder 55 of each roll unit just after the restrained bar 31 passing through the roll thereof, thereby rotating the arms 52 in a clockwise direction and causing the roll 53 to support the mandrel bar 1 and thus supporting the mandrel bar 1 on the pass line P - P to allow its smooth backward movement and prevent the occurrence of bending and the like.

However, the known roll units of the above-described construction has the danger of causing any fault in 55 the sensors, delay in the operation of the hydraulic cylinders and the like and are not reliable and therefore there has existed a need forthe development of roll units which are reliable and stable in operation.

The present invention has been made to meet these requirements and it is an object of this invention to provide a novel arrangement of roll units in which each roll supporting arm is adapted to swing about its rotary shaft and the swinging motion of the arms is mechanically associated in synchronism with the 60 forward and backward movements of a restrained bar for moving a mandrel bar, thereby reversibly swinging the roll units so as to avoid a collision between the rolls and the restrained bar and also positively supporting the shell and the mandrel bar on the pass line by a suitable number of the rolls.

It is another object of the invention to provide such novel arrangement of roll units in which in order to prevent the danger of a situation arising where when the rolling of the shell is completed so that the mandrel 65 2 GB 2 116 890 A 2 bar is pulled out of the shell the mandrel bartop is lowered from the pass line by an amount corresponding to the shell wall thickness thus frequently tending to bend the mandrel bar, atthe same timethatthe mandrAbar is pulled out of the shell the roll units located nearthe rolling mill entry are raised quickly so as to support the mandrel bar on the pass line.

It is still another object of the invention to provide such novel arragement of roll units in which a part or all 5 of the rolls of the plurality of roll units are forcibly and accurately driven into swinging so as to facilitate the forward and backward movements of the mandrel bar and the forward movement of the shell.

It is still another object of the invention to provide a novel inlettable for roll units in which when the shell size andlor the mandrel bar diameter are changed, the vertical positions of the rolls are adjusted to the proper heights so as to align the center of the mandrel bar and the shell with the pass line and thereby effect the rolling.

The above and other objects, features and advantages of the invention will become apparentfrom the following description taken in conjunction with the accompanying drawings.

Figure 1 is a side view showing schematically the basic construction of a prior art inlettable and the condition in which a shell having a mandrel bar inserted thereinto is just before its entry into a rolling mill.15 Figure2 is a side view for explaining the operation of the roll units in the condition where the shell is being rolled in an advanced position with respect to its position in Figure 1.

Figure 3 is a plan view showing schematically the basic construction of an embodiment of the invention.

Figure 4 is a side view of Figure 3 with a part thereof being eliminated.

Figure 5 is a plan view showing schematically an embodiment of a restrained bar drive system.

Figure 6 is a plan view showing schematically an embodiment of a roll gear drive.

Figure 7 is a plan view showing an embodiment of roll units.

Figure 8 is a side view of Figure 7.

Figure 9 is a longitudinal sectional view taken along the line 1 - 1 of Figure 7.

Figure 10 is a longitudinal sectional view showing another embodiment of the roll units in correspondence 25 to Figure 9.

Figure 11 is a front view showing another embodiment of the roll gear drive.

Figure 12 is a longitudinal sectional view taken along the line 11 - 11 of Figure 11.

Figure 13 is a schematic diagram for explaining the relationship between the path of the restrained bar top and the contacting time of the rolls with the mandrel bar or the shell.

The present invention will now be described in greater detail with reference to Figures 3 and 4, in which numeral 1 designates a mandrel bar, 2 a shell, and 3 a restrainer for the mandrel bar 1 which includes a restrained bar 31 having a coupler 32 for the mandrel bar 1 and racks 33 and 33a and pinions 34 and 34a adapted to engage with the racks 33 and 33a, respectively and move the restrained bar 31 in the forward or backward direction. Designated at T is an inlet table on which are arranged a plurality of roll units 6 and 7 (a 35 total of nine units in the Figure) and the most of the roll units, i.e., the roll units 6 located remote from the restrained bar 31 each comprises a pair of parallel rolls. Namely, each roll unit 6 includes a rotary shaft 61, a pair of arms 62 and 62a fixedly mounted on the shaft 61 and a pair of rolls 64 and 64a respectively mounted fixedly on shafts 63 and 63a rotatably supported between the arms 62 and 62a. Each of the roll units 7 which are smaller in number and located nearerto the restrained bar 31 includes a single roll, that is, it comprises a 40 rotary shaft 71, a pair of arms 72 and 72a fixedly mounted on the shaft 71 and a roll 74fixedly mounted on a shaft 73 rotatably mounted between the arms 72 and 72a. A gear unit 81 comprising bevel gears 81a and 81 b is arranged between the pinions 34 and 34a for driving the restrained bar 31 and a drive motor 8 and a transmission shaft 83 is extended from the gear unit 81 in parallel with the mandrel bar 1. A gear drive 84 including bevel gears 84a and 84b is arranged on the intermediary portion of the transmission shaft 83 for 45 each of the roll units 6 and 7 and an output shaft 85 of each gear drive 84 is connected to the rotary shaft 61 or 71 of the roll unit 6 or 7. As a result, the arms 62, 62a, 72 and 72a of the roll units 6 and 7 are reversibly swung in synchronism with the forward and backward movements of the restrained bar 31 (hereinafter the roll units 6 and 7 may sometimes be referred to as G) to @). The Figures showthe case where the minority roll units 5C) G) and @ each has a single roll mounted therein and each of the roll units @ to @) has two rolls mounted 50 therein. Numeral 6a designates pinch rolls.

Referring to Figure 5, there is illustrated an exemplary basic construction of the drive system forthe restrained bar 31. Note that the illustrated drive system includes eight drive motors arranged in the form of four consecutive two-high motors (the lower motors are not shown). Since the roll units G) and (2) are closer to the restrained bar 31, they must be swung earlier than the other to prevent them from colliding with the 55 restrained bar 31 and moreover the mandrel bar 1 is deflected to a lesser extent thus making it necessary for them to include only one roll. ON the contrary, each of the roll units @) to @ are located remote from the restrained bar 1 than the former and the mandrel bar 1 is deflected to a greater extent thus making it necessary to increase the contact time between the roll units and the mandrel bar 1 or the shell 2 and inount two rolls in each of them. The outputs of motors 8 and 8a are transmitted to the pinion 34 by a drive shaft 82 60 through gear trains 81 c and 81 d of the gear unit 81 and the outputs of motors 8b and 8c are transmitted to the pinion 34b by a drive shaft 82b through gear trains 81 e and 81f thereby synchronously driving the restrained bar 31. Also, the output of the motor 8a is transmitted to the gear drive 84 of each of the roll units 6 and 7 through a gear train 81 g and the output shaft 83 of the bevel gears 81 a and 81 b. Note that the shaft 83 may be replaced with a chain, belt or the like to effect the transmission of power.

1 p 11 P 3 GB 2 116 890 A 3 Referring to Figure 6 showing an exemplary basic construction of a drive unit for the roils 64 and 64a (while the drive unit for the two-rol I units is shown, the same construction is used for the single-rol I units), a double gear 86 is loosely mounted on an output shaft 85 of the one bevel gear 84b in the gear drive 84 and one gear 86a of the double gear 86 is meshed with an intermediate gear 87 which is loosely mounted on the shaft attached to the arm 62. The intermediate gear 87 is meshed with gears 88 and 88a which are respectively mounted on the shafts 63 and 63a of the rolls 64 and 64a, and the rotation of the other bevel gears 84c and 84d mounted fixedly on the shaft 83 is transmitted to the other gear 86b of the double gear 86 through a shaft 85a and a gear 89. As a result, the arms 62 and 62a are swung about the shaft 61 in synchronism with the pinions 34 and 34a, etc., and also the rolls 64 and 64a are swung in the forward and backward directions in synchronism with the pinions 34 and 34b. 10 Referring to Figures 7,8 and 9, there is illustrated an example of the roll units 6 in which the rotary shaft 61 is coupled by a universal joint 100 to the output shaft 85 of the gear drive 84 which is swingable in synchronism with the pinion 34 for driving the restrained bar 31, and the roll units G) to @ are swung at different reduction ratios (although some of the units use the same reduction ratio) in a direction A when the restrained bar 31 is advanced in a direction a and in a direction B when the restrained bar 31 is retreated in a 15 direction b (see Figure g).

Numerals 62 and 62a designate arms fixedly mounted on the rotary shaft 1, 64 and 64a rolls fixedly mounted on shafts 63 and 63a which are rotatably mounted in the arms 62 and 62a through bearings. Numerals 65 and 65a designate rocker arms which are loosely mounted on the rotary shaft 61 on the outer side of the arms 62 and 62a, respectively, and they have their one end pivotably mounted on fixed supporting points 66 and 66a, respectively, and their other end respectively coupled to the forward end of connecting rods 68 and 68a of screw jacks 67 and 67a, respectively. Numeral 69a designates a shaft for transmitting the driving force of a motor 69 to the other screw jack 67a. Numerals 110 and 1 10a designate bases for supporting the rocker arms 65 and 65a, respectively, and attached to mounts 111 and 111 a arranged on the bases 110 and 11 Oa are the shafts forming the fixed supporting points 66 and 66a of the rocker arms 65 and 65a. As a result, if the diameter of the mandrel bar 1 and/or the size of the shell 2 are changed, the motor 69 (Figure 7) is operated so that the screw jacks 67 and 67a are raised or lowered and the positions of the rolls 64 and 64a are adjusted to any given heights.

Referring to Figure 10, there is illustrated a longitudinal sectional view similar to Figure 9 showing another embodiment of the roll unit 6. As shown in the Figure, quick lifting mechanisms (hereinafter referred to as a 30 quick mechanisms) are added to the rolls 64 and 64a and the remaining construction is substantially the same with the construction of Figure 9. The construction of this quick mechanism will now be described with respect to the one arranged on one side. The quick mechanism of the rolls 64 and 64a includes a hydraulic cylinder 90 connected to the forward end of the connecting rod 68 of the screw jack 67 and its operating rod 91 is connected to one end of the rocker arm 65 whose other end is extended from the supporting point 66 so 35 as to face a limit means 92 positioned below the free end of the rocker arm 65. Numeral 93a designates a shaft for transmitting the driving force of a motor 93 to the other limit means 92a.

As mentioned previously, when the mandrel bar 1 is pulled out of the shell 2, its top is lowered from the pass line by an amount equal to the wall thickness of the shell 2 thus involving the danger of causing a bend in the mandrel bar 1. In accordance with the invention, at the same time that the mandrel bar 1 is pulled out 40 of the shell 2 the hydraulic cylinder 90 is operated so that the operating rod 91 is raised and the rocker arm 65 is swung about the supporting point 66 in the direction A, thereby quickly raising the rolls 64 and 64a and holding the mandrel bar 1 on the pass line. The limit means 92 limits the range of rotation of the rocker arm so as to limit its height and thereby place the rolls 64 and 64a in given raised positions. In this case, the adjustment of the raised positions of the rolls 64 and 64a can be effected without the provision of the limit 45 means 92 if the operating rod 91 is adapted to come into the desired raised position through the adjustment of the oil quantity in the hydraulic cylinder 90. The quick mechanisms of this type are incorporated in some of the roll units.

Figures 11 and 12 show still another embodiment of the gear drive of the rolls 64 and 64a, in which the one gear 86a of the double gear 86 mounted on the rotary shaft 61 through a bearing is connected to the gears 88 50 and 88a fixedly mounted on the shafts 63 and 63a of the rolls 64 and 64a through the intermediate gear 87 and the other gear 86b of the double gear 86 is meshed with a gear 89a of the motor 89 (see Figures 6 and 7) for driving the rolls 64 and 64a. In this way, the rolls 64 and 64b can be swing independently of the pinions 34 and 34a. The roll gear drives of this type are incorporated in some or all of the roll units.

Referring now to Figure 13, the operation of this embodiment will now be described. The various data of 55 the roll units (5) to @) in this embodiment are shown in the following Table 1. Figure 13 is a schematic operation explanatory diagram showing the relationship between the mandrel bar 1 and the shell 2 and the roll units T to @) in the like manner as Figure 4, and Figure 14 is a graph showing the relationship between the path of the restrained bar top and the contact time between the roll units (1) to @ and the mandrel bar 1 or the shell 2 with the ordinate representing the time and the absissa representing the distance of travel of 60 the mandrel bar 1. Figures 13 and 14 are shown in correspondence to each other. Note that symbol D designates the roll unit having the gear drive for the rolls 64 or 74 and Q designates the roll unit having the quick mechanisms. Also, in Figure 14 the length of each bar at the position of each roll unit indicates the length of time that each roll is in contact with the mandrel bar 1 or the shell 2. In the case of the roll unit @), for example, t3,, indicates the time that the roll 64 of this roll unit is in contact with the mandrel bar 1 and t3b 65 4 GB 2 116 890 A 4 indicates the time that the other rail 64a is in contact with the mandrel bar. Also, t3,, indicates the non-contact time due to the gap between the rolls 64 and 64a and t3d indicates the time required for preventing a collision with the restrained bar 31. Substantially the same relationship as described so far is applicable to the other roll units. Thus, as will be seen from Figure 14, at any position of the restrained bar 31 the mandrel bar 1 and/or the shell 2 are supported by at least one of the roll units and in this way a continuous supporting 5 structure is provided. Designated by Pe is the advanced end position of the restrained bar top.

CW +1 CM X r_ a) X U) 0 0 CM m CL 1 1 1 1 1 1 1 E 0 00 a) OC CM m CL D- CM LO +. +, CM X - r CR E X E m 0- U) 0 LO (D c) Lq m CM Oi c c) U) 1 (D (9 1 1 1 1 1 1 CL A W E E CO 00 Lq Lq:!t 00 a E E CR LO N CM E z CM C m E E LO N 00 a? 00 (R R2 LO C5 CM (D E > (0 (U 0 U) U) 0 0) 0 C 0 0 E 0 m CL (L) CJ -6 -6 3 > CS 0 CD z C3) c > m 0 0.2 c 0 m E r 0 E cj 0 -6 -6 0 0 U) 3 0 0 cc a) m (D (D cc cc GB 2 116 890 A 5 Referring first to the condition of Figure 13 where the restrained bar 31 starts advancing in the direction a, as shown at a point P. in Figure 14, the mandrel bar l is supported by the rol Is 74 and 64 of the roll units (D and (1) and the shell 2 is supported by the rolls 64 of the roll units @) and @) and the pinch rolls 6a. Of these roll units, the rolls 64 of the roll units @ and @ are rotated about their own axes by the gear drives (the pinch rolls 6a always support the shell 2 and therefore their explanation will be omitted in the description to follow). Then, when the restrained bar 31 is advanced at a high speed in the arrow a direction as shown in Figure 14, the rotary shafts 61 and 71 of the roll units (D to @ which are connected to the driving source with the reduction ratios shown in Table 1 are respectively rotated in a clockwise direction as the restrained bar 31 is moved forward. For instance, at a point Pi, the rolls 74 and 64 of the roll units (D, (2) and @ are swung greatly in the clockwise direction to avoid a collision with the restrained bar 31 and the roll units @) and @ 10 are swung so as to support the mandrel bar 1. Also the roll units (2) and @) are swung so as to support the shell 2.

In this way, each of the rolls 74 and 64 of the roll units (D to @ is swung clockwise (in the direction c) within the range of arrows c and dand the mandrel bar 1 and the shell 2 are thus supported by one to six of the rolls at all times thereby introducing the shell 2 into the rolling mill. Since each of the rolls will be swung 15 to a position lower than the pass line P - P by an amount equal to or greater than a thickness t3 by the time that the restrained bar 31 reaches above each roll, there is no danger of the restained bar 31 striking against the rolls. In the condition just before the completion of the rolling of the shell 2, each of the rolls 64 is at the position c in Figure 13.

When the rolling of the shell 2 is over so that the mandrel bar 1 is moved backward in the direction of the 20 arrow b, the rolls 74 and 64 of the roll units G) to @ are swung in a counterclockwise direction (the direction d). When the restrained bar 31 and the mandrel bar 1 are each moved back to a given position so that the mandrel bar 1 is pulled out of the shell 2, the top of the mandrel bar 1 is lowered by the wall thickness of the shell 2 and displaced from the pass line P - P correspondingly thus giving rise to the danger of bending the mandrel bar 1 or making the backward movement of the mandrel bar 1 not smooth. For this reason, in accordance with the invention, as soon as the mandrel bar 1 is removed from the shell 2, the rolls 64 of the rollunits@,Q) and@ located near the mill entry end are raised quickly by the quick mechanisms and the mandrel bar 1 is supported along the pass line P - P.

When the mandrel bar 1 is moved backward at a high speed in the direction of the arrow b, the rolls 74 and 64 of the roll units G) to @ are swung in the counterclockwise direction and the mandrel bar 1 is always 30 supported by several of the rolls. After completion of the backward movement of the mandrel bar 1, the roll units 6 previously raised quickly by the quick mechanisms are lowered by the time that the next shell 2 is entered.

While, in the above-description, the various data of the roll units are shown in Table 1, the present invention is not intended to be limited thereto and these data may of course be changed in accordance with 35 the shell rolling speed and various other conditions. Further, the driving means of the mandrel bar driving restrained bar include the racks, it is possible to use any other restraining and feeding means such as a chain drive or cylinder unit. Still further, while the exemplary constructions of the gear system, the roll units, the quick mechanism and the roll gear drives are shown, various other means may be used provided that the same objects and functions are attained.

From the foregoing description it will be seen that in accordance with the invention, by virtue of the fact the rotary shafts each having the roll or rolls mounted thereon through the arms are connected to the driving source of the mandrel bar restrainer through the reduction gears and the shafts are swung reversibly in synchronism with the forward and backward movements of the mandrel bar thereby preventing the restrainer and the rolls striking against each other and supporting the shell and the mandrel bar by a suitable 45 number of the rolls, there is realized a restrained mandrel mill including an inlet table which is positive in operation and having no danger of any collision between the mandrel bar and the rolls. Thus, in accordance with the invention there is no danger of causing any damage to the restrainer and the rolls and the operating efficiency is improved.

Claims (8)

1. An inlet table fora restrained mandrel mill comprising:

a plurality of roll means arranged in the direction of a pass line to support a mandrel bar and/or a shell to be rolled; and means for mechanically transmitting to said roll means a movement of a restrained bar for moving said mandrel bar; such that each of said roll means is swung reversibly about a rotary shaft of arms having at least one roll mounted thereon in response to a forward movement or backward movement of said restrained bar.

2. An inlet table according to claim 1, wherein at least one of said roll means includes quick means for 60 quickly displacing the roll or rolls thereof vertically.

3. An inlet table according to claim 1, wherein the most of said roll means positioned remote from said restrained bar each includes two rolls, and wherein the other minority of said roll means each includes a single roll.

4. An inlet table according to claim 1, wherein each of said roll means comprises a rotary shaft secured to 65 6 GB 2 116 890 A 6 one end of each of a pair of arms, at least one roll mounted on the other end of each of said arms, and transmission means connected to said rotary shaft to transmit thereto a power derived from drive means of said restrained bar, and wherein at least one of said roll means effects the transmission of power between said roll and said tranmission means through a double gear loosely mounted on said rotary shaft and a 5 plurality of gears.

5. An inlet table according to claim 4, wherein the rotary shaft of each said roll means is loosely mounted between a pair of rocker arms each having one end forming a fixed supporting point and the other end forming a movable supporting point.

6. An inlet table according to claim 5, wherein quick lift means adapted for quick vertical movement and lo slow lift means adapted for slow vertical movement are consecutively connected to the movable supporting 10 point of each of said rocker arms.

7. An inlet table according to claim 6, wherein the fixed supporting point of each said rocker arm is extended further to form a free end, and wherein adjustable limit means is arranged opposite to said free end so as to control the height thereof.

8. An inlet table fora restrained mandrel mill, the table being substantially as hereinbefore described 15 with reference to, and as illustrated in, Figures 3 to 9 and 13, or Figures 3 to 9 and 13 as modified in Figure 10 or in Figures 11 and 12, of the accompanying drawings.

A Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1983.

Published by The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.

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